1. Field of the Invention
The present invention relates to an electronic musical instrument, and more particularly, to an electronic musical instrument which can selectively execute a musical performance by a stringed instrument with frets such as a guitar and a musical performance by a fretless stringed instrument such as a violin.
2. Description of the Related Art
With recent rapid development of electronic techniques, electronic stringed instruments have been developed which can generate musical tones with multifarious timbres through the same picking operation as done with traditional natural stringed instruments. A string trigger type electronic stringed instrument is one of such electronic stringed instruments. This electronic stringed instrument detects the fret position of a string, presently depressed, by means of a pitch designation status detector provided on the fingerboard side, to thereby designate a corresponding pitch, detects the status of a picking operation conducted on a string by means of a string trigger sensor provided on the body side, and generates a musical tone with a given timbre from this string trigger sensor at the pitch designated by the pitch designation status detector. The feature of this string trigger type electronic stringed instrument lies in its simple structure according to which the beginning of string vibration is detected by the string trigger sensor, a musical tone is generated upon this detection, and the pitch of the musical tone to be generated is determined by a pitch designation signal from the pitch designation status detector.
Traditional natural stringed instruments are classified into two types; the first type is an acoustic guitar or the like which has frets provided on the fingerboard, and the other is a violin or the like which has no frets provided on the fingerboard. Accordingly, two types of electronic stringed instruments, namely, an electronic stringed instrument with frets and a fretless electronic stringed instrument, have been developed. The former type has fret status detecting means for each of a number of frets provided on the fingerboard. This type of electronic stringed instrument is disclosed in, for example, U.S. Pat. Nos. 4,235,141, 4,336,734, 4,630,520, 4,658,690 and 4,723,468. The latter type of electronic stringed instrument has belt-shaped pitch status detecting means provided on the fingerboard, and this means comprises a number of switches. This electronic stringed instrument is disclosed in U.S. Pat. No. 4,805,510, for example.
According to the conventional fret type electronic stringed instrument, however, one fret status detecting means is simply provided for each fret, so that only one pitch is set by one fret status detecting means. If, with one fret being depressed, the fingering position at the fret position is slightly or finely changed, the pitch of a musical tone to be generated cannot be finely altered in accordance with the change in fingering position. In other words, this type of electronic stringed instrument has a shortcoming such that it cannot produce the same vibrato effect as obtained by performing a vibrato operation on a so-called violin type stringed instrument which has no frets on the fingerboard.
According to the conventional fretless electronic stringed instrument, fingering positions are detected by the aforementioned many pitch status detecting means. When a finger tip is moved within a range corresponding to the same fret position, therefore, the pitch of a musical tone to be generated is slightly changed in accordance with the finger movement. Although this instrument can produce the aforementioned vibrato effect of a violin type stringed instrument, it cannot provide the same musical effect as obtained by a fret-using stringed instrument, such as a guitar.